Your search for "n20-cblkb1" revealed the following:
NEW Cisco N20-CBLKB1 Single Slot Blade Blanking Panel for UCS 5108 Server
SKU: NSN-7222
Condition: New
Shipping: Overnight Options
Warranty: 365 days
Cisco N20-CBLKB1 Single Slot Blade Blanking Panel for UCS 5108 Server
SKU: NSH-7697
Condition: Seller refurbished
Shipping: Overnight Options
Warranty: 365 days